Apple Shake 4 - Manual (Page 577)

Chapter 20 Rotoscoping 577
Here, a point is inserted and moved toward
the center at the first keyframe. At the
second keyframe’s position, the shape is still
round because Shake has maintained the
smooth quality of the segment. If you
instead turn on the Propagate buttons
when you modify a point, the second
keyframe’s point position is also modified.
For example, go back to keyframe 1, enable
Propagate Forward, and insert a new point,
dragging it outward. Jump to the second
keyframe, and the new point is positioned
in a relatively similar fashion in the second
keyframe.
If you have several keys, Propagate Forward
or Backward can slow down your
interactivity.
To quickly scrub through an animation,
toggle to Release or Manual Update mode
(in the upper-right corner of the interface),
and then move the playhead. The shapes
draw in real time, but are not rasterized.
Button Usage Example